JPH03261020A - Vacuum valve for vacuum circuit breaker - Google Patents

Abstract

PURPOSE:To increase arc adsorbing capability without increasing the outside dimension of an arc shield by shaping the arc shield in a cylindrical form coaxial with a contact and the inside surface in roughness. CONSTITUTION:An arc shield 7 is arranged coaxial with the fixed contact 8 and the moving contact 9 of a vacuum circuit breaker and made in a cylindrical form. The arc shield 7 has the inside surface provided with a groove 7A, e.g. and shaped in roughness. The width and the depth of the groove 7A are made smaller than the thickness of the arc shield 7 to give almost no influence on the plate weight of the total arc shield. As a result, the heat capacity of the arc shield 7 is almost not subject to change in spite of the existence of the groove 7A and in addition the inside surface is increased by the groove 7A without increasing the outer dia.. It is thus possible to obtain greater arc adsorbing capability and improve the performance of the circuit breaker.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vacuum valve for a vacuum circuit breaker that switches on and off current in a high vacuum, and particularly to the structure of a vacuum valve equipped with an arc shield.

[Conventional technology]

Vacuum circuit breakers open contacts in a high vacuum of approximately 10 mmHg to interrupt current.They have excellent interrupting performance, are small and lightweight, pose no risk of fire or explosion, and require almost no maintenance and inspection, and are widely used in industry. It has been widely used since the beginning.

FIG. 4 shows an example of the structure of a conventional vacuum valve for a vacuum circuit breaker.
are hermetically joined, and this internal space is maintained at a high vacuum.

A fixed rod 4 passes through the cover plate 3 and is hermetically joined to the cover plate 3, and a movable rod 6 connects the cover plate 2 via a bellows 5 coaxially attached to the outer circumference of the cover plate 2. It penetrates and is hermetically joined to allow movement in the axial direction.

A fixed contact 8 is fixed to the inner end surface of the fixed rod 4, and a movable contact 9 is fixed to the inner end surface of the movable rod 6, and the fixed contact 8 and the movable contact 9 constitute a pair of contacts. A cylindrical arc shield 7 is arranged around the contacts 8 and 9 coaxially with the contacts, and the metal vapor generated when the current is interrupted is adsorbed on its inner surface to improve interrupting performance.

[Problem to be solved by the invention]

When the contacts are opened during current interruption, metal vapor is generated due to the arc. This metal vapor is adsorbed onto the inner surface of the arc shield provided around the contacts, but this adsorption ability greatly affects the breaking performance of the circuit breaker. The adsorption capacity of an arc shield is mainly determined by its adsorption area and heat capacity.

Conventionally, an arc shield consisting of a metal cylinder with a certain heat capacity and thickness is used, but since the inner surface of the cylinder faces a window due to its structure, it was necessary to enlarge the inner surface to further improve the blocking performance. In this case, the cylinder itself had to be made larger, which resulted in the problem of making the vacuum valve larger.

On the other hand, attempts have been made to make the peripheral surface of the cylinder bellows-like by drawing, as shown in the arc shield 7 in Fig. 5, to increase the inner surface. There was also the problem that the dimensions of the vacuum valve became thicker and the vacuum valve became larger.

An object of the present invention is to solve the above-mentioned problems and provide a vacuum valve for a vacuum circuit breaker in which the inner surface of the arc shield is increased and the adsorption area for metal vapor is increased without increasing the external dimensions of the arc shield. .

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention maintains a high vacuum inside an insulating tube whose both ends are hermetically sealed by cover plates, and an air-tight tube is inserted into the insulating tube through one cover plate. A fixed contact is provided on the inner end surface of the coupled fixed rod, and a movable contact is provided on the inner end surface of the movable rod that passes through the other cover plate and is airtightly coupled so as to be movable in the axial direction via the bellows. The fixed contact and the movable contact form a pair of contacts, and in a vacuum valve for a vacuum circuit breaker, the arc shield is provided around these contacts with an inner surface that adsorbs metal vapor generated during current interruption. It is made of coaxial cylindrical metal with an uneven inner surface.

[For production]

In the vacuum valve for a vacuum circuit breaker of the present invention, the arc shield is made of a cylindrical metal coaxial with the contact, and its inner surface is made uneven. As a result, the area of the inner surface, which was conventionally flat, is greatly increased, and the adsorption area for metal vapor can be increased without increasing the external dimensions of the arc shield.

〔Example〕

FIG. 1(a) is a sectional view of a vacuum valve for a vacuum circuit breaker according to an embodiment of the present invention. Circular lid plates 2 and 3 are tightly joined to both ends of a cylindrical insulating tube 1,
A movable rod 6 passes through the cover plate 2 via a bellows 5 attached to its outer periphery, and is securely joined to the cover plate 2 so as to be movable in the axial direction.

A fixed contact 8 is fixed to the inner end surface of the fixed rod 4, and a movable contact 9 is fixed to the inner end surface of the movable rod 6, and the fixed contact 8 and the movable contact 9 constitute a pair of contacts. An arc shield 7 is arranged around the contacts 8 and 9, and its inner surface adsorbs metal vapor generated when the current is interrupted. The steps up to this point are the same as the conventional vacuum valve for vacuum circuit breakers shown in FIG. In this embodiment, the arc shield 7 is made of a cylindrical metal coaxial with the contact, and a plurality of slits are provided on its inner surface. FIG. 1(b) is a sectional view of a main part of the A section of the arc shield 7 in FIG. 1(a), showing the detailed structure of the inner surface of the arc shield 7. Reference numeral 7A denotes a plurality of slits provided on the inner surface of the arc shield 7, whereby the inner surface of the arc shield 7 becomes uneven and its inner surface area increases greatly.

For example, if grooves with depth α and rl are provided at a pitch of 2d, the inner surface area will increase approximately twice. In the example of FIG. 1, the problem is that the grooves are provided in the circumferential direction, but they may also be provided in the axial direction. Alternatively, they may be provided in the circumferential direction and in the axial direction, and in this case, the inner surface area increases approximately three times.

Since the adsorption capacity of an arc shield is mainly determined by its adsorption area and heat capacity, by increasing the inner surface area of the arc shield to increase the adsorption area, the adsorption capacity can be greatly increased. By making the width and depth of this groove smaller than the plate thickness of the arc shield, the plate weight of the arc shield is hardly affected, and therefore its heat capacity is also hardly changed. Of course, the plate thickness of the arc shield may be increased by an amount corresponding to the weight corresponding to the removed groove. In this case, if the width and depth of the groove are made smaller than the thickness of the arc shield as described above, the increase in thickness can be made extremely small.

With this structure, the attraction area can be greatly increased without substantially increasing the external dimensions of the arc shield.

FIG. 2 shows different embodiments of the present invention, in which (a) is a sectional view of the vacuum valve, and (b) is an A of the arc shield 7 in (a).
FIG. In this example, the inner surface of the arc shield 7 is provided with a plurality of recesses 7B, thereby making the inner surface of the arc shield 7 uneven and increasing its inner surface area.

FIG. 3 shows still another embodiment of the present invention, in which (a) is a sectional view of a vacuum valve, and (b) is an arc shield 7 of (a).
FIG. In this example, a plurality of convex portions 7C are provided on the inner surface of the arc shield 7, thereby making the inner surface of the arc shield 7 uneven and increasing its inner surface area. In the embodiments shown in FIGS. 2 and 3 as well, the attraction area can be greatly increased without increasing the external dimensions of the arc shield.

〔Effect of the invention〕

According to the present invention, in a vacuum valve for a vacuum circuit breaker, the inner surface of the arc shield is made uneven, so that the inner surface area can be increased, for example, in width, depth, and height, without increasing the outer dimensions of the arc shield. By providing grooves with a 2d pinch, the number could be doubled. This makes it possible to further improve the interrupting performance of the vacuum valve for the vacuum circuit breaker without increasing its size.

[Brief explanation of drawings]

FIG. 1 shows the structure of a vacuum valve for a vacuum circuit breaker according to an embodiment of the present invention, in which a) is a cross-sectional view, (b) is a cross-sectional view of a main part of the arc shield 7 of (a), and FIG. Fig. 1 shows the structure of a vacuum valve for a vacuum circuit breaker according to different embodiments of a)
is a cross-sectional view, (b) is a cross-sectional view of a main part of the arc shield 7 of (a), and FIG. B)
4 is a sectional view of a conventional vacuum valve for a vacuum circuit breaker, and FIG. 5 is a sectional view of a different example of a conventional vacuum valve for a vacuum circuit breaker. 1: Insulating cylinder, 2, 3: Cover plate, 4: Fixed rod, 5: Bellows, 6: Movable rod, 7: Arc shield, 7A: Groove (for arc shield), 7B: Recess (for arc shield), 7C : Convex part (of arc shield), 8: Fixed contact,
9: Movable contact. Sign spread Hei 5 ZbllJ:? (J (3)

Claims (1)

[Claims] 1) The inside of an insulating tube whose both ends are hermetically sealed by cover plates is maintained at a high vacuum, and a fixed contact is attached to the inner end surface of a fixed rod that passes through one cover plate and is connected airtightly inside the insulating tube. A movable contact is provided on the inner end surface of a movable rod that passes through the other cover plate and is airtightly coupled to be movable in the axial direction via a bellows, and the fixed contact and the movable contact have a pair of contacts. In a vacuum valve for a vacuum circuit breaker, the arc shield is made of a cylindrical metal coaxial with the contacts, and is equipped with an arc shield that adsorbs metal vapor generated during current interruption around these contacts on its inner surface. A vacuum valve for vacuum circuit breakers characterized by an uneven surface.